fix(ssr): apply theme CSS vars during SSR and enable client hydration

- ThemeService: remove isPlatformBrowser guard so CSS custom properties
  are applied during SSR/prerender — server-rendered HTML now carries the
  correct color scheme and gradients (fixes missing colors on test site).

- main.ts: add provideClientHydration() so Angular preserves the server-
  rendered DOM on the client instead of destroying and rebuilding it
  (fixes jarring full-page reload between static and dynamic versions).

- Tests: update theme.service.spec.ts to match new behaviour, expand
  coverage with gradient tests and empty-value handling (9 tests).
  Fix structured-data.component.spec.ts import paths. All 54 tests pass.

src/app/services/event.service.spec.ts

@@ -0,0 +1,59 @@
+// Load the JIT compiler BEFORE any Angular router/common imports
+import '@angular/compiler';
+
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { Injector } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { EventService } from './event.service';
+import { firstValueFrom } from 'rxjs';
+
+// Mock the app-config service
+vi.mock('./app-config.service', () => ({
+  getAppConfig: () => ({ apiBaseUrl: 'http://localhost:8000' }),
+}));
+
+describe('EventService — SSR error handling', () => {
+  let httpMock: any;
+  let service: EventService;
+
+  beforeEach(() => {
+    httpMock = {
+      get: vi.fn(),
+      post: vi.fn(),
+      put: vi.fn(),
+      delete: vi.fn(),
+    };
+
+    const injector = Injector.create({
+      providers: [
+        { provide: HttpClient, useValue: httpMock },
+        EventService,
+      ],
+    });
+    service = injector.get(EventService);
+  });
+
+  it('should return empty array when API fails (SSR fallback)', async () => {
+    const { throwError } = await import('rxjs');
+    httpMock.get.mockReturnValue(throwError(() => new Error('Network error')));
+
+    const result = await firstValueFrom(service.getEvents());
+    expect(result).toEqual([]);
+  });
+
+  it('should return empty array when API fails with active filter', async () => {
+    const { throwError } = await import('rxjs');
+    httpMock.get.mockReturnValue(throwError(() => new Error('Network error')));
+
+    const result = await firstValueFrom(service.getEvents(true));
+    expect(result).toEqual([]);
+  });
+
+  it('should call the API endpoint', async () => {
+    const { of } = await import('rxjs');
+    httpMock.get.mockReturnValue(of([{ id: 1, name: 'Test Event' }]));
+
+    await firstValueFrom(service.getEvents());
+    expect(httpMock.get).toHaveBeenCalled();
+  });
+});